1. Field of the Invention
Known supporting means operate with so-called lamina hooks which are disposed on a threaded rod. A compressing means is disclosed in British patent 2 131 300. A distracting means is disclosed in U.S. Pat. No. 4,383,438. The threaded rod bridges a plurality of vertebras and is not suited to act on vertebras which are disposed between the lamina hooks. The thread of the rod is used to fix the lamina hooks. Before using the supporting means a distraction or, respectively, compression has to be provided by means of an additional device.